https://sourceware.org/bugzilla/show_bug.cgi?id=32584
Bug ID: 32584
Summary: ld.bfd slowdown linking some linux kernels
Product: binutils
Version: 2.39
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: arnd at arndb dot de
Target Milestone: ---
I noticed a slowdown in link times between linux kernels 6.12 and 6.13,
bisected it to a commit that changed the section ordering, as well as
binutils-2.39 and higher, see my report on the kernel mailing list, see
https://lore.kernel.org/lkml/20250120212839.1675696-1-a...@kernel.org/.
Rong Xu further narrowed down the cause of the problem on the binutils side to
to commit fba1ac87dcb7 ("Fix the sorting algorithm for reloc entries").
I created a smaller test case for reproducing the issue, but it still exceeds
the 10MB limit for binutils bugzilla, so I uploaded the file to
https://drive.google.com/file/d/1M_ccr8RINzfjpU1qA5qA0rhRIGgDOFix/view?usp=sharing
time x86_64-linux-gnu-ld -m elf_x86_64 -z noexecstack --emit-relocs
--discard-none -z max-page-size=0x200000 --gc-sections --build-id=sha1
--orphan-handling=warn --script=./arch/x86/kernel/vmlinux.lds --strip-debug -o
.tmp_vmlinux1 --whole-archive vmlinux.a init/version-timestamp.o
--no-whole-archive --start-group lib/lib.a arch/x86/lib/lib.a --end-group
.tmp_vmlinux0.kallsyms.o
real 0m31.128s
user 0m30.472s
sys 0m0.277s
time x86_64-linux-ld-2.36 -m elf_x86_64 -z noexecstack --emit-relocs
--discard-none -z max-page-size=0x200000 --gc-sections --build-id=sha1
--orphan-handling=warn --script=./arch/x86/kernel/vmlinux.lds --strip-debug -o
.tmp_vmlinux1 --whole-archive vmlinux.a init/version-timestamp.o
--no-whole-archive --start-group lib/lib.a arch/x86/lib/lib.a --end-group
.tmp_vmlinux0.kallsyms.o
real 0m1.142s
user 0m0.898s
sys 0m0.237s
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